PKS 1514-241 (AP Libræ) is a low red shift (z=0.049) BL Lac type object with a compact, flat-spectrum radio core and is a
well studied blazar. It has not been identified by EGRET and is
therefore of interest in a comparison between gamma-ray loud and
gamma-ray quiet AGN; EGRET detected not only the powerful AGN at
large red shifts, but also AGN which are considerably less luminous at
low red shifts (e.g. PKS 0521-365 and Mrk 421). Fitchel et al.
[1994] placed an upper limit to greater than 100 MeV photons of 0.7 
10 
cm 
s 
for PKS 1514-241. The typical blazar characteristics of
high optical polarisation and variability have been well demonstrated
for this source. The optical polarisation measured by Kinman [1976]
varied over the range 2 - 6% and rapid variability has been observed
at optical wavelengths [Webb et al. 1988].
Figure: Low contour 
1%. Peak 1.9 Jy/beam. Beam, 6.1 2.5 mas @ -87.9 
PKS 1514-241 has previously only been observed with single baseline
VLBI [Preston et al. 1985; Mollenbrock et al. 1996] and shows compact structure on
intercontinental baselines. The observations described here were made
at a frequency of 8.4 GHz and are the first VLBI imaging
observations. The image (Figure 4.11) shows a strong core component of
1.9 Jy and a short jet-like extension at a position angle of
approximately 195 .
Several investigators have published images of
the extended radio emission of PKS 1514-241. Stannard and McIlwrath
[1982] present a MERLIN image at 0.4 GHz with 2.''5 resolution which
shows a 5'' extension at a position angle of approximately
125 . However, Antonucci and Ulvestad [1985] present a 20 cm
VLA A configuration image of PKS 1514-241 with a resolution of 1.''2
arcseconds which shows a 23'' extension from the core at a position
angle of approximately 100 . Likewise, Morganti et al.
[1993] present a C+B 
configuration VLA image at a frequency of
4.885 GHz of PKS 1514-241. The image has a resolution of 4.''4
4.''8 and shows a 21''
extension at a position angle of approximately 90 . The
higher quality and more recent observations from the VLA are consistent
between Antonucci and Ulvestad [1985] and Morganti et al.
[1993]. The mas-scale and arcsecond-scale structures are
therefore misaligned by approximately 100 .
From the VLBI image the de-convolved core dimensions of 1.3 0.9 mas and the total core flux density of 2.2 Jy give an observed radio core brightness temperature of 3.0 10 
K at 8.4 GHz. This value is very low and is due to the fact that only short baselines (< 1000 km) were obtained with these observations. This value for the brightness temperature will not be useful for comparison with the data for the other six sources since those data were obtained at 4.8 GHz, with baselines exceeding 3000 km. Mollenbrock et al. [1996] observed PKS 1514-241 as part of the VSOP pre-launch survey on an intercontinental baseline at 22 GHz and found an observed brightness temperature at that frequency of > 1.46 
10 
K.